Transmitter apparatus of mobile device and operation method thereof

ABSTRACT

In a transmitter apparatus of a mobile device, a radio frequency unit has transmitting terminals for sending wireless signals of different frequency bands. Transmission filters are respectively connected to the transmitting terminals and perform a filtering process for the signal of each frequency band. A first switch has a single output terminal and input terminals respectively connected to the transmission filters, performing a switching operation to connect one of the input terminals and the output terminal in response to a control signal. A power amplifier amplifies the signal transmitted through the output terminal of the first switch. A second switch has a single input terminal connected to the power amplifier, and output terminals corresponding to the transmission filters. The second switch performs a switching operation to connect the input terminal and one of the output terminals in response to the control signal.

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

The present application is related to and claims the benefit under 35 US. C. §119 a of a Korean patent application filed in the KoreanIntellectual Property Office on Apr. 22, 2010 and assigned Serial No.10-2010-0037400, and the entire disclosure of which is herebyincorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to a mobile device and, moreparticularly, to a transmitter apparatus with a single power amplifierin the mobile device for supporting two or more frequency bands and alsoto an operation method thereof.

BACKGROUND OF THE INVENTION

Normally a mobile device refers to a kind of electronic device based onmobility and portability. With remarkable growth of relatedtechnologies, a great variety of mobile devices are increasinglypopular. A mobile device may now offer a variety of end-user functions,in addition to a traditional voice call function, such as a shortmessage service (SMS), a digital camera, a music player, a digitalbroadcast service, an e-mail service, an instant messenger service, andthe like.

As market demands for various multimedia services of high qualityincrease, a new mobile device may support a high-speed datacommunication service. For instance, mobile devices that support LTE(Long Term Evolution) services are gradually increasing. These LTEservices are offered using a number of different frequency bands.

In order to support such LTE services, a conventional mobile deviceshould support multiple bands. Therefore, such a mobile device mayinclude a plurality of transmitter apparatuses each of which correspondsto each frequency band. Each transmitter apparatus includes atransmission/reception (TX/RX) isolation unit, a power amplifier, atransmission filter, and the like, suitable for a corresponding specificfrequency band. Since different transmitter apparatuses are used fordifferent frequency bands, a conventional mobile device may oftenconfront a shortage of space for accommodating components. Additionally,too many components may cause complicated circuitry of transmitterapparatuses and an increase of production costs.

SUMMARY OF THE INVENTION

To address the above-discussed deficiencies of the prior art, it is aprimary object to minimize the number of power amplifiers used for atransmitter apparatus of a mobile device that supports two or morefrequency bands.

According to one aspect of the present invention, a transmitterapparatus of a mobile device is provided. The transmitter apparatusincludes a radio frequency (RF) unit having at least two transmittingterminals configured to send wireless signals of different frequencybands. The transmitter apparatus also includes at least two transmissionfilters each being connected to each of the transmitting terminals ofthe RF unit and configured to perform a filtering process for thewireless signal of each frequency band. The transmitter apparatusfurther includes a first switch having at least two input terminals anda single output terminal, each input terminal being connected to eachtransmission filter, the first switch configured to perform a switchingoperation to connect one of the input terminals and the output terminalin response to a control signal. The transmitter apparatus also includesa power amplifier configured to amplify the wireless signal transmittedthrough the output terminal of the first switch. The transmitterapparatus further includes a second switch having a single inputterminal and at least two output terminals, the input terminal beingconnected to the power amplifier, each output terminal corresponding toeach transmission filter, the second switch configured to perform aswitching operation to connect the input terminal and one of the outputterminals in response to the control signal. The transmitter apparatusfurther includes at least two duplexers each being connected to each ofthe output terminals of the second switch. The transmitter apparatusalso includes an antenna configured to transmit the wireless signaloutputted through one of the duplexers, and a control unit configured togenerate the control signal.

According to another aspect of the present invention, a method foroperating a transmitter apparatus of a mobile device is provided. Themobile device includes a first switch having a single output terminaland at least two input terminals connected respectively to at least twotransmission filters, a second switch having a single input terminal andat least two output terminals connected respectively to at least twoduplexers, and disposed between the output terminal of the first switchand the input terminal of the second switch. The method includescontrolling a switching operation of the first switch such that thepower amplifier is connected to the transmission filter selectedcorresponding to a specific frequency band. The method also includescontrolling a switching operation of the second switch such that thepower amplifier is connected to the duplexer selected corresponding tothe specific frequency band.

According to other aspect of the present invention, a mobile device isprovided. The mobile device includes a display unit. The mobile devicealso includes an input unit and a transmitter unit. The transmitter unitincludes a radio frequency (RF) unit having at least two transmittingterminals configured to send wireless signals of different frequencybands. The transmitter unit also includes at least two transmissionfilters each being connected to each of the transmitting terminals ofthe RF unit and configured to perform a filtering process for thewireless signal of each frequency band. The transmitter unit furtherincludes a first switch having at least two input terminals and a singleoutput terminal, each input terminal being connected to eachtransmission filter, the first switch configured to perform a switchingoperation to connect one of the input terminals and the output terminalin response to a control signal. The transmitter unit also includes apower amplifier configured to amplify the wireless signal transmittedthrough the output terminal of the first switch. The transmitter unitfurther includes a second switch having a single input terminal and atleast two output terminals, the input terminal being connected to thepower amplifier, each output terminal corresponding to each transmissionfilter, the second switch configured to perform a switching operation toconnect the input terminal and one of the output terminals in responseto the control signal. The transmitter unit also includes at least twoduplexers each being connected to each of the output terminals of thesecond switch. The transmitter unit further includes an antennaconfigured to transmit the wireless signal outputted through one of theduplexers, and a control unit configured to generate the control signal.

Aspects of the present invention may minimize the number of the poweramplifiers used for the transmitter apparatus of the mobile device. Thismay secure space for accommodating components and simplify the circuitryof the transmitter apparatus. Also, since relatively high-priced poweramplifiers are minimized in number, total production cost of the mobiledevice may be reduced.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, itmay be advantageous to set forth definitions of certain words andphrases used throughout this patent document: the terms “include” and“comprise,” as well as derivatives thereof, mean inclusion withoutlimitation; the term “or,” is inclusive, meaning and/or; the phrases“associated with” and “associated therewith,” as well as derivativesthereof, may mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like; and theterm “controller” means any device, system or part thereof that controlsat least one operation, such a device maybe implemented in hardware,firmware or software, or some combination of at least two of the same.It should be noted that the functionality associated with any particularcontroller may be centralized or distributed, whether locally orremotely. Definitions for certain words and phrases are providedthroughout this patent document, those of ordinary skill in the artshould understand that in many, if not most instances, such definitionsapply to prior, as well as future uses of such defined words andphrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates a configuration of a mobile device in accordance withan embodiment of the present invention;

FIG. 2 illustrates a method for operating a transmitter apparatus of amobile device in accordance with one embodiment of the presentinvention; and

FIG. 3 illustrates a method for operating a transmitter apparatus of amobile device in accordance with another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 3, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged device. This invention may,however, be embodied in many different forms and should not be construedas limited to the exemplary embodiments set forth herein. Rather, thedisclosed embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art. The principles and features of thisinvention may be employed in varied and numerous embodiments withoutdeparting from the scope of the invention.

Furthermore, well known or widely used techniques, elements, structures,and processes may not be described or illustrated in detail to avoidobscuring the essence of the present invention. Although the drawingsrepresent exemplary embodiments of the invention, the drawings are notnecessarily to scale and certain features may be exaggerated or omittedin order to better illustrate and explain the present invention.

A mobile device according to embodiments of this invention may include,but is not limited to, an electronic device supporting a multi-band andincludes a mobile communication terminal, a personal digital assistant(PDA), a smart phone, and the like. Embodiments of this invention to bedescribed hereinafter employ a mobile communication terminal as a goodrepresentative of the mobile device.

FIG. 1 is a block diagram illustrating the configuration of a mobiledevice in accordance with an embodiment of the present invention.

Referring to FIG. 1, the mobile device 100 includes an antenna 10, atransmission/reception (TX/RX) isolation unit 180, a first switch 150, apower amplifier 160, a second switch 170, a transmission filter unit140, a radio frequency (RF) unit 130, a memory unit 120, and controlunit 110. The TX/RX isolation unit 180 includes a plurality ofduplexers, and the transmission filter unit 140 includes a plurality oftransmission filters.

The mobile device 100 having the above elements performs switchingoperations for the first switch 150 disposed between the transmissionfilters and the power amplifier 160 and for the second switch 170disposed between the power amplifier 160 and the duplexers, depending ona frequency band. Therefore, the mobile device 100 can transmit awireless signal through the transmission filter and duplexer selected inaccordance with a specific frequency band. Hereinafter, the mobiledevice 100 that supports four frequency bands will be described.

The RF unit 130 may establish a communication channel for a voice calland also establish a communication channel for transmission of data suchas images. For instance, the RF unit 130 may establish a voice callchannel, a data transmission channel, and a video call channel withabase station. The RF unit 130 may include an RF transmitter thatup-converts the frequency of a signal and an RF receiver that amplifieswith low-noise a received signal and down-converts the frequency of thesignal.

The RF unit 130 can transmit and receive a wireless signal at two ormore different frequency bands. For this, the RF unit 130 may include atleast two transmitting terminals and at least two receiving terminals.For instance, as shown, the RF unit 130 may include four transmittingterminals TX1, TX2, TX3, and TX4 and four receiving terminals RX1, RX2,RX3, and RX4. The RF unit 130 may transmit a wireless signal through aselected one of four transmitting terminals under the control of thecontrol unit 110. Specifically, the first transmitting terminal TX1sends a wireless signal at the first frequency band, and the secondtransmitting terminal TX2 sends a wireless signal at the secondfrequency band. Similarly, the third transmitting terminal TX3 sends awireless signal at the third frequency band, and the fourth transmittingterminal TX4 sends a wireless signal at the fourth frequency band. Also,the first receiving terminal RX1 receives a wireless signal at the firstfrequency band, the second receiving terminal RX2 receives a wirelesssignal at the second frequency band, the third receiving terminal RX3receives a wireless signal at the third frequency band, and the fourthreceiving terminal RX4 receives a wireless signal at the fourthfrequency band. For instance, the first frequency band may be the LTEBand 12, the second frequency band may be the LTE Band 13, the thirdfrequency band maybe the LTE Band 14, and the fourth frequency band maybe the LTE Band 17.

The RF unit 130 does not necessarily include four transmitting terminalsand four receiving terminals. If the mobile device 100 merely supportstwo frequency bands, the RF unit 130 may include two transmittingterminals and two receiving terminals only. Namely, the number oftransmitting or receiving terminals maybe varied according to the numberof LTE bands supported by the mobile device 100.

The transmission filter unit 140 is a device that performs a filteringprocess for a wireless signal transmitted from the RF unit 130. Thetransmission filter unit 140 may include at least two transmissionfilters, depending on the number of frequency bands supported by themobile device 100. For instance, as shown, the transmission filter unit140 may have the first transmission filter 41 connected at one endthereof to the first transmitting terminal TX1 of the RF unit 130, thesecond transmission filter 42 connected at one end thereof to the secondtransmitting terminal TX2 of the RF unit 130, the third transmissionfilter 43 connected at one end thereof to the third transmittingterminal TX3 of the RF unit 130, and the fourth transmission filter 44connected at one end thereof to the fourth transmitting terminal TX4 ofthe RF unit 130. The first transmission filter 41 performs a filteringprocess for a signal being transmitted at the first frequency band, andthe second transmission filter 42 performs a filtering process for asignal being transmitted at the second frequency band. Similarly, thethird transmission filter 43 performs a signal filtering process at thethird frequency band, and the fourth transmission filter 44 performs asignal filtering process at the fourth frequency band. Thesetransmission filters 41 to 44 may be formed of SAW (surface acousticwave) filters. Each of the transmission filters 41 to 44 may beconnected at the other end thereof to a corresponding one of inputterminals 51 to 54 of the first switch 150.

The first switch 150 may include a plurality of input terminals, asingle output terminal, and one or more control terminals. For instance,as shown, the first switch 150 may have the first input terminal 51connected to the first transmitting filter 41, the second input terminal52 connected to the second transmitting filter 42, the third inputterminal 53 connected to the third transmitting filter 43, the fourthinput terminal 54 connected to the fourth transmitting filter 44, asingle output terminal 55 connected to the power amplifier 160, and twocontrol terminals C1 and C2 through which a control signal forcontrolling a switching operation of the first switch 150 is inputted.

In response to the control signal of the control unit 110, the firstswitch 150 performs a switching operation such that one of thetransmission filters 41 to 44 maybe connected to the power amplifier160. For instance, if a control signal (0, 0) is inputted to the firstand second control terminals C1 and C2, the first switch 150 connectsthe first transmission filter 41 and the power amplifier 160. If acontrol signal (0, 1) is inputted, the first switch 150 connects thesecond transmission filter 42 and the power amplifier 160. If a controlsignal (1, 0) is inputted, the first switch 150 connects the thirdtransmission filter 43 and the power amplifier 160. If a control signal(1, 1) is inputted, the first switch 150 connects the fourthtransmission filter 44 and the power amplifier 160.

The number of the input terminals and control terminals of the firstswitch 150 maybe varied according to the number of frequency bandssupported by the mobile device 100. For instance, if the mobile device100 supports two different frequency bands, the first switch 150 mayinclude two input terminals and a single control terminal. If the mobiledevice 100 supports eight different frequency bands, the first switch150 may include eight input terminals and three control terminals.

The power amplifier 160 is a device for increasing the power of a signaltransmitted from the RF unit 130 such that the signal can be sent as faras a base station. Since the power amplifier 160 is well known in theart, it may not be described or illustrated in detail herein.Particularly, the power amplifier 160 of this invention can be used incommon at two or more different frequency bands supported by the mobiledevice 100. The power amplifier 160 is connected at one end thereof tothe output terminal 55 of the first switch 150 and connected at theother end thereof to an input terminal 75 of the second switch 170.Namely, under the control of the control unit 110, the power amplifier160 amplifies the power of a signal transmitted through one of the firstto fourth transmission filters 41 to 44 and then delivers the amplifiedsignal to the second switch 170.

The second switch 170 may include a single input terminal, a pluralityof output terminals, and one or more control terminals. For instance, asshown, the second switch 170 may have the first output terminal 71connected to the first duplexer 81, the second output terminal 72connected to the second duplexer 82, the third output terminal 73connected to the third duplexer 83, the fourth output terminal 74connected to the fourth duplexer 84, a single input terminal 75connected to the power amplifier 160, and two control terminals C3 andC4 through which a control signal for controlling a switching operationof the second switch 170 is inputted.

In response to the control signal of the control unit 110, the secondswitch 170 performs a switching operation such that one of the duplexers81 to 84 may be connected to the power amplifier 160. For instance, if acontrol signal (0, 0) is inputted to the first and second controlterminals C3 and C4, the second switch 170 connects the first duplexer81 and the power amplifier 160. If a control signal (0, 1) is inputted,the second switch 170 connects the second duplexer 82 and the poweramplifier 160. If a control signal (1, 0) is inputted, the second switch170 connects the third duplexer 83 and the power amplifier 160. If acontrol signal (1, 1) is inputted, the second switch 170 connects thefourth duplexer 84 and the power amplifier 160.

The number of the output terminals and control terminals of the secondswitch 170 may be varied according to the number of frequency bandssupported by the mobile device 100.

The TX/RX isolation unit 180 is a device that separates a transmittedsignal and a received signal. The TX/RX isolation unit 180 may be formedof a duplexer. The TX/RX isolation unit 180 may include at least twoduplexers, depending on the number of frequency bands supported by themobile device 100. For instance, the TX/RX isolation unit 180 may have afirst duplexer 81 that is connected to the first output terminal 71 ofthe second switch 170 and divides a wireless signal of the firstfrequency band into a transmitted signal and a received signal; a secondduplexer 82 that is connected to the second output terminal 72 of thesecond switch 170 and divides a wireless signal of the second frequencyband into a transmitted signal and a received signal; a third duplexer83 that is connected to the third output terminal 73 of the secondswitch 170 and divides a wireless signal of the third frequency bandinto a transmitted signal and a received signal; and a fourth duplexer84 that is connected to the fourth output terminal 74 of the secondswitch 170 and divides a wireless signal of the fourth frequency bandinto a transmitted signal and a received signal. Received signalsdivided through the first to fourth duplexers 81 to 84 are inputted tothe first to fourth receiving terminals RX1 to RX4 of the RF unit 130,respectively.

The antenna 10 is a device for transmitting and receiving a wirelesssignal. Particularly, the antenna 10 is a wideband antenna capable oftransmitting and receiving a wireless signal of two or more differentfrequency bands. For instance, the antenna 10 may transmit and receive awireless signal of at least two different frequency bands used foroffering LTE services. Specifically, the antenna 10 may transmit andreceive wireless signals corresponding to the LTE Bands 12, 13, 14 and17 in a 700 MHz band.

The memory unit 120 stores an operating system (OS) of the mobile device100, various applications associated with optional functions such as asound output, an image view, a video play, a broadcast signal output,and the like, and related user data. Particularly, the memory unit 120of this invention may store a control program that retrieves operatorinformation contained in a subscriber identity module (SIM) card (notshown) in a booting process or when an SIM card change event occurs, andthen controls the first and second switches 150 and 170 such that awireless signal may be transmitted through a specific transmissionfilter and duplexer selected in response to a specific frequency band ofa current network operator. Additionally, if the mobile device 100 hastwo or more SIM cards, the control program may find a specific SIM cardcorresponding to the transmission event when any transmission eventoccurs, and then control a transmission of a wireless signal to use aspecific transmission filter and duplexer selected in response to thespecific SIM card.

The control unit 110 performs a function to control the whole operationof the mobile device 100 and signal flows among internal blocks of themobile device 100, and also performs a function to process datatransmitted or received through the RF unit 130. Particularly, thecontrol unit 110 of this invention may retrieve operator informationcontained in the SIM card in a booting process of the mobile device 100and then control the first and second switches 150 and 170 such that aspecific transmission filter and duplexer corresponding to a specificfrequency band of a current network operator may be connected to thepower amplifier 160. Similarly, when the SIM card change event occurs,the control unit 110 may retrieve operator information contained in anew SIM card and then control the first and second switches 150 and 170such that a specific transmission filter and duplexer corresponding tothe retrieved operator information may be connected to the poweramplifier 160.

If the mobile device 100 has two or more SIM cards, the control unit 110may retrieve operator information from a master SIM card in a bootingprocess and then control the first and second switches 150 and 170 suchthat a specific transmission filter and duplexer corresponding to aspecific frequency band of a current network operator may be connectedto the power amplifier 160. Thereafter, when any transmission eventoccurs, the control unit 110 may find a specific SIM card correspondingto the transmission event and then control the first and second switches150 and 170 such that a specific transmission filter and duplexercorresponding to the specific SIM card may be connected to the poweramplifier 160. When the transmission event is terminated, the controlunit 110 may put the first and second switches 150 and 170 in apredetermined default state. For instance, in response to thetermination of the transmission event, the control unit 110 may controlthe first and second switches 150 and 170 such that a specifictransmission filter and duplexer corresponding to the master SIM cardmay be connected to the power amplifier 160.

In order to control switching operations of the first and secondswitches 150 and 170, the control unit 110 has the first controlterminal SW1_C and the second control terminal SW2_C therein. Thesecontrol terminals SW1_C and SW2_C may be GPIO (general purpose inputoutput) terminals. The number of control terminals SW_C may be variedaccording to the number of frequency bands supported by the mobiledevice 100. For instance, if the mobile device 100 supports frequencybands from five to eight, the number of the control terminals is three.

The control unit 110 may simultaneously control switching operations ofthe first and second switches 150 and 170 through the control terminalsSW1_C and SW2_C. Alternatively, the control unit 110 may control bothswitches 150 and 170 through a single control terminal or separatelycontrol the switches 150 and 170 through respective control terminals.Although FIG. 1 depicts the first and second switches 150 and 170 andthe power amplifier 160 as separate elements, at least two of them maybe integrated into a single module.

Although not illustrated, the mobile device 100 of this invention mayessentially or selectively include any other elements such as a displayunit, a input unit, a camera module, a short range communication module,a location based service module, a broadcast receiving module, a digitalsound play module such as an MP3 module, an Internet access module, andthe like. According to a digital convergence tendency today, suchelements may be varied, modified and improved in various ways, and anyother elements equivalent to the above elements may be additionally oralternatively equipped in the mobile device 100. As will be understoodby those skilled in the art, some of the above-mentioned elements in themobile device may be omitted or replaced with another.

FIG. 2 is a flow diagram illustrating a method for operating atransmitter apparatus of a mobile device in accordance with anembodiment of the present invention.

Referring to FIGS. 1 and 2, the mobile device 100 may perform a bootingprocess (block 201). This booting process may start when a given powerkey is merely selected or when such a power key is pressed for a giventime.

Then the control unit 110 may retrieve operator information contained inthe SIM card (block 203) and then find a specific frequency band of acurrent network operator (block 205) . For the above, the memory unit120 or the SIM card may store information about a service frequency bandof each individual network operator.

Next, the control unit 110 may control a switching operation of thefirst and second switches 150 and 170 according to the specificfrequency band (block 207). For instance, if a current operator offers aservice at the first frequency band (e.g., the LTE Band 12), the controlunit 110 may enable the first switch 150 to connect the firsttransmission filter 41 and the power amplifier 160 and also enable thesecond switch 170 to connect the first duplexer 81 and the poweramplifier 160. Similarly, if a current operator offers a service at thesecond frequency band (e.g., the LTE Band 13), the control unit 110 mayenable the first switch 150 to connect the second transmission filter 42and the power amplifier 160 and also enable the second switch 170 toconnect the second duplexer 82 and the power amplifier 160. If a currentoperator offers a service at the third frequency band (e.g., the LTEBand 14), the control unit 110 may enable the first switch 150 toconnect the third transmission filter 43 and the power amplifier 160 andalso enable the second switch 170 to connect the third duplexer 83 andthe power amplifier 160. If a current operator offers a service at thefourth frequency band (e.g., the LTE Band 17), the control unit 110 mayenable the first switch 150 to connect the fourth transmission filter 44and the power amplifier 160 and also enable the second switch 170 toconnect the fourth duplexer 84 and the power amplifier 160.

After the booting process is completed, the control unit 110 may enterinto an idle state (block 209). Then the control unit 110 may determinewhether any SIM card change event occurs (block 211). If so, the controlunit 110 may return to the above block 203. Namely, the control unit 110may retrieve operator information from a new SIM card and then controlthe first and second switches 150 and 170 such that a specifictransmission filter and duplexer corresponding to the retrieved operatorinformation may be connected to the power amplifier 160. However, ifthere is no SIM card change event, the control unit 110 may perform anyother particular function (block 213) . For instance, the control unit110 may perform a music player function, a camera function, and thelike, at a user's request or may keep in an idle state.

The embodiment described above is associated with a mobile device thatincludes only one SIM card. Hereinafter, it will be supposed that themobile device has two or more SIM cards.

FIG. 3 is a flow diagram illustrating a method for operating atransmitter apparatus of a mobile device in accordance with anotherembodiment of the present invention.

The mobile device 100 to be described hereinafter is in a state after agiven booting process is completed. In this state, the power amplifierin the mobile device 100 is connected to a specific transmission filterand duplexer corresponding to a master one of all the SIM cards. Thisstate will be referred to as a default state.

Referring to FIGS. 1 and 3, the control unit 110 may determine whetherany transmission event occurs (block 301). If there is no transmissionevent, the control unit 110 may perform any particular function (block321). For instance, the control unit 110 may perform a music playerfunction, a camera function, and the like, at a user's request or maykeep in an idle state. If any transmission event occurs, the controlunit 110 may further determine whether the transmission event correlatesto the first frequency band (block 303). Normally when a signal of atransmission request is inputted, the mobile device 100 having two ormore SIM cards may display a window that allows a user to select one ofthe SIM cards for the transmission event. Then the control unit 110 mayfind a specific frequency band correlated with the transmission event,depending on the result of selection.

If the transmission event correlates with the first frequency band, thecontrol unit 110 may activate the first transmission filter 41 and thefirst duplexer 81 (block 305). Namely, the control unit 110 may enablethe first switch 150 to connect the first transmission filter 41 and oneend of the power amplifier 160 and also enable the second switch 170 toconnect the first duplexer 81 and the other end of the power amplifier160.

If the transmission event does not correlate with the first frequencyband, the control unit 110 may further determine whether thetransmission event correlates to the second frequency band (block 307).If the transmission event correlates with the second frequency band, thecontrol unit 110 may activate the second transmission filter 42 and thesecond duplexer 82 (block 309). Namely, the control unit 110 may enablethe first switch 150 to connect the second transmission filter 42 andone end of the power amplifier 160 and also enable the second switch 170to connect the second duplexer 82 and the other end of the poweramplifier 160.

If the transmission event does not correlate with the second frequencyband, the control unit 110 may further determine whether thetransmission event correlates to the third frequency band (block 311).If the transmission event correlates with the third frequency band, thecontrol unit 110 may activate the third transmission filter 43 and thethird duplexer 83 (block 313). Namely, the control unit 110 may enablethe first switch 150 to connect the third transmission filter 43 and oneend of the power amplifier 160 and also enable the second switch 170 toconnect the third duplexer 83 and the other end of the power amplifier160. If the transmission event does not correlate with the thirdfrequency band, the control unit 110 may activate the fourthtransmission filter 44 and the fourth duplexer 84 (block 315). Namely,the control unit 110 may enable the first switch 150 to connect thefourth transmission filter 44 and one end of the power amplifier 160 andalso enable the second switch 170 to connect the fourth duplexer 84 andthe other end of the power amplifier 160.

Next, the control unit 110 may determine whether the transmission eventis terminated (block 317). If the transmission event is not terminatedyet, the control unit 110 returns to the above block 303. If thetransmission event is terminated, the control unit 110 may put the firstand second switches 150 and 170 in a default state (block 319). Asdiscussed above, in the default state, a specific transmission filterand duplexer corresponding to a master SIM card are connected to thepower amplifier 160.

Although the disclosure set forth herein describes a specific embodimentwhere four frequency bands are used for services, this is exemplary onlyand not to be considered as a limitation of the present invention. Thisinvention may be favorably applied to other embodiments where two ormore frequency bands are used for services.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

1. A transmitter apparatus of a mobile device, the transmitter apparatuscomprising: a radio frequency (RF) unit having at least two transmittingterminals configured to send wireless signals of different frequencybands; at least two transmission filters each being connected to each ofthe transmitting terminals of the RF unit and configured to perform afiltering process for the wireless signal of each frequency band; afirst switch having at least two input terminals and a single outputterminal, each input terminal being connected to each transmissionfilter, the first switch configured to perform a switching operation toconnect one of the input terminals and the output terminal in responseto a control signal; a power amplifier configured to amplify thewireless signal transmitted through the output terminal of the firstswitch; a second switch having a single input terminal and at least twooutput terminals, the input terminal being connected to the poweramplifier, each output terminal corresponding to each transmissionfilter, the second switch configured to perform a switching operation toconnect the input terminal and one of the output terminals in responseto the control signal; at least two duplexers each being connected toeach of the output terminals of the second switch; an antenna configuredto transmit the wireless signal outputted through one of the duplexers;and a control unit configured to generate the control signal.
 2. Thetransmitter apparatus of claim 1, wherein the control unit is furtherconfigured to retrieve operator information contained in a subscriberidentity module (SIM) card in a booting process and then to control thefirst and second switches such that the transmission filter and theduplexer selected corresponding to a specific frequency band of acurrent network operator are connected to the power amplifier.
 3. Thetransmitter apparatus of claim 1, wherein the first and second switchesare simultaneously controlled by means of the same control signal. 4.The transmitter apparatus of claim 1, wherein the mobile devicecomprises at least two subscriber identity module (SIM) cards.
 5. Thetransmitter apparatus of claim 4, wherein the control unit is furtherconfigured to determine the SIM card correlated with a transmissionevent when the transmission event occurs, and then to control the firstand second switches such that the transmission filter and the duplexerselected corresponding to the SIM card are connected to the poweramplifier.
 6. The transmitter apparatus of claim 5, wherein the controlunit is further configured to put the first and second switches in apredetermined default state when the transmission event is terminated.7. A method for operating a transmitter apparatus of a mobile devicethat includes a first switch having a single output terminal and atleast two input terminals connected respectively to at least twotransmission filters, a second switch having a single input terminal andat least two output terminals connected respectively to at least twoduplexers, and disposed between the output terminal of the first switchand the input terminal of the second switch, the method comprising:controlling a switching operation of the first switch such that thepower amplifier is connected to the transmission filter selectedcorresponding to a specific frequency band; and controlling a switchingoperation of the second switch such that the power amplifier isconnected to the duplexer selected corresponding to the specificfrequency band.
 8. The method of claim 7, further comprising: retrievingoperator information contained in a subscriber identity module (SIM)card of the mobile device in a booting process and then determining thespecific frequency band of a current network operator in order tocontrol the switching operation of the first and second switches.
 9. Themethod of claim 7, further comprising: if the mobile device comprises atleast two subscriber identity module (SIM) cards, determining thespecific frequency band of the SIM card correlated with a transmissionevent when the transmission event occurs, in order to control theswitching operation of the first and second switches.
 10. The method ofclaim 9, further comprising: putting the first and second switches in apredetermined default state when the transmission event is terminated.11. The method of claim 10, wherein the transmission filter and theduplexer corresponding to a master SIM card of the SIM cards areconnected to the power amplifier in the default state.
 12. The method ofclaim 7, wherein the first and second switches are simultaneouslycontrolled by means of a same control signal.
 13. A mobile devicecomprising: a display unit; an input unit; and a transmitter unit, thetransmitter unit comprising: a radio frequency (RF) unit having at leasttwo transmitting terminals configured to send wireless signals ofdifferent frequency bands; at least two transmission filters each beingconnected to each of the transmitting terminals of the RF unit andconfigured to perform a filtering process for the wireless signal ofeach frequency band; a first switch having at least two input terminalsand a single output terminal, each input terminal being connected toeach transmission filter, the first switch configured to perform aswitching operation to connect one of the input terminals and the outputterminal in response to a control signal; a power amplifier configuredto amplify the wireless signal transmitted through the output terminalof the first switch; a second switch having a single input terminal andat least two output terminals, the input terminal being connected to thepower amplifier, each output terminal corresponding to each transmissionfilter, the second switch configured to perform a switching operation toconnect the input terminal and one of the output terminals in responseto the control signal; at least two duplexers each being connected toeach of the output terminals of the second switch; an antenna configuredto transmit the wireless signal outputted through one of the duplexers;and a control unit configured to generate the control signal.
 14. Themobile device of claim 13, wherein the control unit is furtherconfigured to retrieve operator information contained in a subscriberidentity module (SIM) card in a booting process and then to control thefirst and second switches such that the transmission filter and theduplexer selected corresponding to a specific frequency band of acurrent network operator are connected to the power amplifier.
 15. Themobile device of claim 13, wherein the first and second switches aresimultaneously controlled by means of the same control signal.
 16. Themobile device of claim 13, wherein the mobile device comprises at leasttwo subscriber identity module (SIM) cards.
 17. The mobile device ofclaim 16, wherein the control unit is further configured to determinethe SIM card correlated with a transmission event when the transmissionevent occurs, and then to control the first and second switches suchthat the transmission filter and the duplexer selected corresponding tothe SIM card are connected to the power amplifier.
 18. The mobile deviceof claim 17, wherein the control unit is further configured to put thefirst and second switches in a predetermined default state when thetransmission event is terminated.
 19. The mobile device of claim 13,further comprising: a memory unit configured to store an operatingsystem (OS) of the mobile device.
 20. The mobile device of claim 13,wherein the at least two duplexers comprise four duplexers.